Keystone

Supports standard RISC-V ISA and sub-ISAs, enabling portability across different RISC-V platforms with minimal engineering effort, as stated in its goal to enable TEE on almost all RISC-V processors.

Allows TEE features to be customized using platform-specific primitives or non-standard sub-ISAs, borrowing from software-defined networking for flexible adaptation to various security needs.

Reuses implementation across platforms to reduce hardware integration, verification, and development costs, making novel TEE designs more accessible and affordable.

Evolved from a research tool to an incubation-stage project with industry-standard cryptography and protocols, facilitating the transition from academic ideas to production-ready systems.